Movement management method using distributed mobile ip

ABSTRACT

In the Mobile IPv4 network in the present invention, FA control servers ( 7   a,    7   b ) that process only Mobile IP signaling, and IP tunnel routers ( 8   a,    8   c ), being an IP tunnel endpoint, which also function as a default router with respect to a mobile node MN, form an FA function (referred to as a virtual FA). Further, an HA control server ( 9 ) that processes only Mobile IP signaling, and an IP tunnel router ( 8   b ), being an IP tunnel endpoint, form an HA function (referred to as a virtual HA). Here, the relation between the FA control servers ( 7   a,    7   b ) and the IP tunnel routers ( 8   a,    8   c ), and the relation between the HA control server ( 9 ) and the IP tunnel router ( 8   b ) are such that the former is a Media Gateway Controller (MGC) and the latter is a Media Gateway (MG). The FA control server ( 7   a ) notifies a mobile node MN ( 2 ) of the own address as an FA care-of address, in the form of a regular broadcast or query response. The IP tunnel router ( 8   a ) constituting the virtual FA notifies the mobile node MN ( 2 ) of an address, being a default router, in the form of a regular broadcast or query response.

TECHNICAL FIELD

[0001] The present invention relates to a mobility management techniquefor mobile packet communication.

BACKGROUND ART

[0002] Mobile IP (RFC 2002) has been suggested in the InternetEngineering Task Force (IETF), as a method for maintaining communicationwithout interrupting the session by a mobile node MN, when a terminalhaving an IP address moves across a subnet (see “RFC 2002: IP MobilitySupport” by C. Perkins, IETF Internet Draft, 1996/10, pages 8 to 11).

[0003] This concept is explained in detail in “Detailed Mobile IP” (see“Detailed Mobile IP” by James D. Solomon, Pearson Education Japan, Jul.27, 1998, pages 57 to 77).

[0004]FIG. 13 illustrates an example of communication using the MobileIP. Reference sign 1 a denotes an IP subnetwork, 1 b denotes an IPsubnetwork belonging to a subnet different from the IP subnetwork 1 a, 2denotes a mobile node MN mounted with the Mobile IP, 3 a and 3 b denoteaccess points accommodating the mobile node, 4 denotes a Mobile IPforeign agent (FA), 5 denotes a home agent (HA) controlling the positionof the mobile node 2 as the IP address of the FA, and 6 denotes acommunication partner node (CN) communicating with the mobile node.

[0005] In the Mobile IP, the HA 5 is arranged in the home domain of themobile node (MN) 2, and an IP address belonging to this home domain(hereinafter, “home address”) is allocated to the mobile node (MN) 2 ina fixed manner. The FA address at which the mobile node (MN) 2 ispresent is controlled by the HA 5 as a position of the mobile node (MN)2. Therefore, the mobile node (MN) 2 registers in the HA a new FAaddress (referred to as an FA care-of address) as an address to whichthe mobile node (MN) 2 moves, via the new FA, at a timing of detectingthat the mobile node (MN) 2 moves from under a supervision of the old FAto under the new FA.

[0006] When the CN 6 transmits an IP packet to the mobile node (MN) 2,the HA 5 controlling the FA care-of address of the mobile node (MN) 2captures the packet addressed to the home address of the mobile node(MN) 2, and transfers the captured IP packet to the registered FA 4through an IP tunnel. The transfer through the IP tunnel stands forencapsulating the IP packet received by the HA with an IP header having:

[0007] a sender address: IP address of the HA 5, and

[0008] a destination address: FA care-of address,

[0009] and transferring it to the FA. Upon reception of the encapsulatedIP packet, the FA 4 takes out the original IP packet therefrom, andtransfers it to the mobile node (MN) 2. By this mechanism, movementtransparency of the mobile node (MN) 2 is realized in the Mobile IP.

[0010] When the mobile node (MN) 2 obtains the IP address in the subnetat the moving destination, the mobile node (MN) 2 can directly registerthis IP address (referred to as a collocated care-of address) as anaddress to which the mobile node (MN) 2 moves, in the HA 5. In thiscase, the IP tunnel is set not between the FA 4 and the HA 5, butbetween the mobile node (MN) 2 and the HA 5.

[0011] The IP packet transmission from the mobile node (MN) 2 to the CN6 is performed by transmission via a normal routing or by transmissionvia the IP tunnel.

[0012] In the conventional configuration, since the FA and the HA havefunctions of signaling processing of the Mobile IP and IP tunneltransfer processing of a user packet, the load concentrates on theseparts.

[0013] Generally, the next-generation network has a networkconfiguration in which a control plane for performing signalingprocessing, and a user plane for performing user packet processing areseparately mounted. In such a distributed network, independentdevelopment of the signaling processing and the user packet processing,realization of scalability of each plane, realization of load balancingon each plane, low cost of the general-purpose user packet processor,and high performance and low cost by realizing the signaling processingon a general-purpose computer are expected. However, the Mobile IP doesnot assume such a distributed network, and hence expansion to thenext-generation network is difficult.

[0014] Particularly, in the Mobile IP, the FA assumes a messageinforming the own address, and the mobile node MN regards the senderIP/MAC addresses in this message as the FA, to perform positionregistration signaling, and also regards it as a default router totransmit the user data. This indicates that one IP address is used forboth signaling and user packet processing, and hence the control planeand the user plane cannot be separated.

[0015] Further, it is not specified how the address information informedby the position registration from the mobile node MN to the HA ishandled, when the control plane and the user plane are separated.

[0016] With regard to the procedure when the mobile node MN does notknow the address of the HA control server, it is not specified how it ischanged, when the control plane and the user plane are separated.

DISCLOSURE OF THE INVENTION

[0017] It is an object of the present invention to at least solve theproblems in the conventional technology.

[0018] A mobility management system according to one aspect of thepresent invention uses a distributed Mobile IP, in a Mobile IP networkwhich allows a mobile node while moving to hold a current communicationsession. The mobility management system includes a foreign agent controlserver that is located in a first subnet where the mobile node islocated, performs Mobile IP signaling; a first IP tunnel router that islocated in the first subnet, and performs IP tunnel transfer; a homeagent control server that is located in a second subnet where the mobilenode is located, and performs Mobile IP signaling; and a second IPtunnel router that is located in the second subnet, and performs IPtunnel transfer. The foreign agent control server and the first IPtunnel router constitute a virtual foreign agent. The home agent controlserver and the second IP tunnel router constitute a virtual home agent.

[0019] A mobility management system according to another aspect of thepresent invention uses a distributed Mobile IP, in a Mobile IP networkwhich allows a mobile node while moving to hold a current communicationsession. The mobility management system includes an access routercontrol server that is located in a first subnet where the mobile node(MN) is located, performs Mobile IP signaling; a first IP tunnel routerthat is located in the first subnet, and performs IP tunnel transfer; ahome agent control server that is located in a second subnet where themobile node is located, and performs Mobile IP signaling; and a secondIP tunnel router that is located in the second subnet, and performs IPtunnel transfer. The access router control server and the first IPtunnel router constitute a virtual access router. The home agent controlserver and the second IP tunnel router constitute a virtual home agent.

[0020] The other objects, features, and advantages of the presentinvention are specifically set forth in or will become apparent from thefollowing detailed descriptions of the invention when read inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021]FIG. 1 is a configuration diagram of a Mobile IP network in whicha control plane and a user plane are separated, being the prerequisitein the first to the eighth embodiments of the present invention;

[0022]FIG. 2 illustrates a control flow of a distributed Mobile IP inthe first embodiment of the present invention;

[0023]FIG. 3 illustrates the operation at the time of receiving an ICMPmessage in a mobile node (MN) 2 in the first, and the third to the fifthembodiments of the present invention;

[0024]FIG. 4 illustrates a processing flow of each apparatus at the timeof executing position registration of the distributed Mobile IP in thefirst embodiment of the present invention;

[0025]FIG. 5 illustrates a control flow of the distributed Mobile IP inthe second embodiment of the present invention;

[0026]FIG. 6 illustrates a processing flow of each apparatus at the timeof executing position registration of the distributed Mobile IP in thesecond embodiment of the present invention;

[0027]FIG. 7 illustrates a flow of IP address notification of an FAcontrol server and an IP tunnel router in the distributed Mobile IP inthe third embodiment of the present invention;

[0028]FIG. 8 illustrates a flow of IP address notification of the FAcontrol server and the IP tunnel router in the distributed Mobile IP inthe fourth embodiment of the present invention;

[0029]FIG. 9 illustrates a control flow of the distributed Mobile IP inthe fifth embodiment of the present invention;

[0030]FIG. 10 illustrates a processing flow of each apparatus at thetime of executing position registration of the distributed Mobile IP inthe fifth embodiment of the present invention;

[0031]FIG. 11 illustrates a flow for obtaining the IP address of an HAcontrol server in the distributed Mobile IP in the sixth embodiment ofthe present invention;

[0032]FIG. 12 illustrates a flow for obtaining the IP address of the HAcontrol server in the distributed Mobile IP in the eighth embodiment ofthe present invention; and

[0033]FIG. 13 illustrates the operation of the conventional Mobile IPnetwork.

BEST MODE FOR CARRYING OUT THE INVENTION FIRST EMBODIMENT

[0034]FIG. 1 is a configuration diagram of a Mobile IPv4 network in thefirst embodiment.

[0035] In FIG. 1, a foreign agent function (hereinafter, “FA function”)includes FA control severs 7 a and 7 b for performing only Mobile IPsignaling processing, and IP tunnel routers 8 a and 8 c for performingonly transfer processing of user data. A home agent function(hereinafter, “HA function”) includes an HA control server 9 forperforming only Mobile IP signaling processing and an IP tunnel router 8b for performing only the transfer processing of user data. The otherconfiguration is the same as that in FIG. 13.

[0036]FIG. 2 is a conceptual diagram illustrating the entire operationof the Mobile IP in the network in illustrated FIG. 1, FIG. 3illustrates the operation at the time of receiving an ICMP message by aterminal, and FIG. 4 illustrates an operation flow of each apparatus atthe time of position registration.

[0037] In this embodiment, the FA control server 7 a regularlybroadcasts the own address of the FA control server as an FA care-ofaddress, as shown by reference numeral 10 in FIG. 2. The message is akind of the ICMP message, and is referred to as a distributed mobileagent advertisement. In order to notify a mobile node (MN) 2 that thestorage network is the distributed Mobile IP network, a code field valueand the like in the message is changed with respect to a normal mobileagent advertisement.

[0038] As illustrated in FIG. 3, the mobile node (MN) 2 receives thedistributed mobile agent advertisement, and recognizes the sender MAC/IPaddresses thereof as the FA control server 7 a, being the destination ofthe position registration signaling. The distributed mobile agentadvertisement may be transmitted as a response to an advertisementrequest message from the mobile node MN.

[0039] The IP tunnel router 8 a regularly broadcasts the IP address,being a default router, with respect to the mobile node MN, as shown byreference numeral 11 in FIG. 2. The message is a normal ICMP routeradvertisement message. As illustrated in FIG. 3, the mobile node (MN) 2receives a router advertisement, and recognizes the sender MAC/IPaddresses as the IP tunnel router 8 a, being the destination of a userpacket. The router advertisement may be transmitted as a response to anadvertisement request message from the mobile node MN.

[0040] The mobile node MN can respectively recognize the FA controlserver on the control plane and the IP tunnel router on the user plane,by respectively receiving the distributed mobile agent advertisement andthe ICMP router advertisement.

[0041] The mobile node MN having recognized the IP addresses of the FAcontrol server 7 a and the IP tunnel router 8 a creates a positionregistration message including the IP address information of a known HAcontrol server 9, and transmits it to the MAC/IP addresses of sender ofthe distributed mobile agent advertisement (reference numeral 13 in FIG.2). The FA control server 7 a receives the position registrationmessage, and obtains the care-of address, being an endpoint of the IPtunnel, in the IP tunnel router 8 a after having scrutinized themessage. The address may be different from the default router address ofthe IP tunnel router 8 a, and this address is determined by referring tothe IP tunnel router 8 a. However, when the FA control server 7 acontrols the resource of the IP tunnel router 8 a, the address may bedetermined independently, without referring to the IP tunnel router 8 a.

[0042] The FA control server 7 a sets the obtained IP tunnel endpointaddress in the IP tunnel router 8 a as a care-of address in the positionregistration message, and transfers the position registration messagewith respect to the address of the HA control server 9 notified from themobile node MN (reference numeral 14 in FIG. 2). The HA control server 9having received the position registration message obtains an address asthe endpoint of the IP tunnel in the IP tunnel router 8 b, after havingstored the IP tunnel information in the message. This address isdetermined by referring to the IP tunnel router 8 b. However, when theHA control server 9 controls the resource of the IP tunnel router 8 b,the address may be independently determined without referring to the IPtunnel router 8 b. The HA control server 9 notifies the IP tunnel router8 b of the IP tunnel endpoint of the opposing IP tunnel router 8 a.

[0043] The HA control server 9 sets the IP tunnel endpoint address inthe obtained IP tunnel router 8 b in the position registration responsemessage as a HA address, and transmits it to the FA control server 7 a(reference numeral 15 in FIG. 2). The FA control server 7 a establishesan IP tunnel (denoted by reference numeral 16 in FIG. 2) between the IPtunnel routers 8 a and 8 b by notifying the IP tunnel router 8 a of theIP tunnel endpoint in the tunnel router 8 b. Thereafter, the FA controlserver 7 a transfers the position registration response message to themobile node (MN) 2 (reference numeral 17 in FIG. 2).

[0044] By a series of operation, as illustrated in FIG. 4, a user datapath is formed via the IP tunnel routers 8 a and 8 b.

[0045] The FA function virtually includes the FA control server and theIP tunnel router, and the HA function virtually includes the HA controlserver and the IP tunnel router. Since the FA control server notifiesthe mobile node (MN) 2 of the own address as the FA care-of address, andthe IP tunnel router constituting the FA function notifies the mobilenode (MN) 2 of the IP address of the default router, the mobile node(MN) 2 can recognize the FA control server and the IP tunnel routerrespectively individually. Therefore, a Mobile IP network in which thecontrol plane and the user plane are separated totally from the mobilenode (MN) 2 to the HA can be constructed. In the Mobile IP network inwhich the control plane and the user plane are separated, the loadbalancing between the control plane and the user plane becomes possible,thereby enabling independent correspondence to upgrade of signaling andspeed-up of the tunnel processing. As a result, an optimized system canbe constructed. The high-speed system can be provided at low cost, byconstructing the control plane on a general-purpose computer system.Since the user plane is cut off from the Mobile IP signaling, the userplane can be general-purpose equipment applicable to a system other thanthe Mobile IP. As a result, a cheap product can be provided.

[0046] When the mobile node (MN) 2 using the FA care-of address performsposition registration, since the IP address at the IP tunnel endpoint inthe IP tunnel router, being a part of the FA function in the Mobile IPprocedure, and the IP address at the IP tunnel endpoint in the IP tunnelrouter, being a part of the HA function are exchanged, the IP tunnel canbe correctly set in the Mobile IP network in which the control plane andthe user plane are separated.

SECOND EMBODIMENT

[0047]FIG. 5 is a conceptual diagram illustrating the entire operationof the Mobile IPv4 network in the second embodiment, and FIG. 6illustrates an operation flow of each apparatus at the time of theposition registration.

[0048] In this embodiment, the FA control server 7 a and the IP tunnelrouter 8 a notify the mobile node (MN) 2 of information in the samemethod as in the first embodiment. In the second embodiment, the mobilenode (MN) 2 selects to use the collocated care-of address of the MobileIPv4 or the Mobile IPv6. In this case, the mobile node (MN) 2 creates aposition registration message including the own IP address of the mobilenode (MN) 2 as the endpoint of the IP tunnel, and transmits the messageto the known HA control server 9 (reference numeral 18 in FIG. 5). TheHA control server 9 having received the position registration messageobtains the address, being the endpoint of the IP tunnel, in the IPtunnel router 8 b after having stored the IP tunnel information in themessage, in the same method as in the first embodiment. At this time,the HA control server 9 notifies the IP tunnel router 8 b of the IPtunnel endpoint of the opposing mobile node (MN) 2.

[0049] The HA control server 9 sets the obtained IP tunnel endpointaddress in the IP tunnel router 8 b in the position registrationresponse message as a HA address, and transmits the message to themobile node (MN) 2 (reference numeral 19 in FIG. 5). At this point intime, the IP tunnel between the mobile node (MN) 2 and the IP tunnelrouter 8 b (reference numeral 16 in FIG. 5) is established.

[0050] By a series of operation, a user data path via the IP tunnelrouter 8 b as illustrated in FIG. 6 is constructed.

[0051] When the mobile node (MN) 2 using the collocated care-of addressperforms position registration, since the IP address of the mobile node(MN) 2 and the IP address of the IP tunnel endpoint in the IP tunnelrouter, being a part of the HA function are exchanged, the IP tunnel canbe correctly set in the Mobile IP network in which the control plane andthe user plane are separated.

THIRD EMBODIMENT

[0052]FIG. 7 is a conceptual diagram illustrating the entire operationof the Mobile IPv4/v6 in the third embodiment.

[0053] In the embodiment, the FA control server 7 a is informed of theIP address as the default router of the mobile node MN by the IP tunnelrouter 8 a (reference numeral 20 in FIG. 7). This is informed at anytime, when the apparatus of the IP tunnel router 8 a is started up orthe operation status of the IP address changes. Alternatively, the FAcontrol server 7 a may statically hold the IP address as theconfiguration data.

[0054] In a path 21 illustrated in FIG. 7, when the FA control server 7a regularly broadcasts the own address as the FA care-of address, the FAcontrol server 7 a broadcasts the IP address as the default router inthe IP tunnel router 8 a at the same time. The message is also a kind ofthe ICMP message and is a distributed mobile agent advertisement.However, the message also includes the ICMP router advertisementinformation other than the information described in the firstembodiment.

[0055] As illustrated in FIG. 3, the mobile node (MN) 2 receives thedistributed mobile agent advertisement and recognizes the sender MAC/IPaddresses as the FA control server 7 a, being the destination of theposition registration signaling. Further, the mobile node MN recognizesthe IP address as the default router from the ICMP router advertisementinformation.

[0056] The mobile node MN can respectively recognize the FA controlserver on the control plane and the IP tunnel router on the user plane,by receiving the ICMP router advertisement in the distributed mobileagent advertisement. However, since the MAC address is unknown as anaddress of the IP tunnel router, the mobile node MN needs to resolve theMAC address from the IP address according to ARP. Particularly, theremay be a constraint on Mobile IP in which the home address of the mobilenode MN cannot be used for ARP. In this case, the mobile node MN usingthe collocated care-of address can use the mechanism.

[0057] Since, the FA control server notifies the mobile node (MN) 2 ofthe own address as the FA care-of address and the address in the IPtunnel router constituting the FA function as the default router IPaddress, the mobile node (MN) 2 can respectively recognize the FAcontrol server and the IP tunnel router. Therefore, a Mobile IP networkin which the control plane and the user plane are separated totally fromthe mobile node (MN) 2 to the HA can be constructed. Particularly, themobile node (MN) 2 using the collocated care-of address can use thismechanism.

FOURTH EMBODIMENT

[0058]FIG. 8 is a conceptual diagram illustrating the entire operationof the Mobile IPv4 in the fourth embodiment.

[0059] In this embodiment, the IP tunnel router 8 a is informed of theIP address of the FA control server, being the care-of address, by theFA control server 7 a (reference numeral 22 in FIG. 8). This is informedat any time, when the apparatus in the FA control server 7 a is startedup or the operation status of the IP address changes. Alternatively, theIP tunnel router 8 a may statically hold the IP address as theconfiguration data.

[0060] In a path 23 in FIG. 8, when regularly broadcasting the IPaddress, being the default router, to the mobile node MN, the IP tunnelrouter 8 a broadcasts the address of the FA control server 7 a as thecare-of address at the same time. The message is a kind of the ICMPmessage and is referred to as a distributed ICMP router advertisement.In order to inform the mobile node MN that the storage network is thedistributed Mobile IP network, a code field value and the like in themessage is changed with respect to a normal ICMP router advertisement.The message also includes the mobile agent advertisement informationother than the information described in the first embodiment. Asillustrated in FIG. 3, the mobile node (MN) 2 receives the distributedICMP router advertisement, and recognizes the sender MAC/IP addressesthereof as the IP tunnel router 8 a, being the default router. Themobile node (MN) 2 also recognizes the IP address of the FA controlserver 7 a from the mobile agent advertisement information.

[0061] The mobile node (MN) 2 can respectively recognize the FA controlserver on the control plane and the IP tunnel router on the user plane,by receiving the mobile agent advertisement in the distributed ICMProuter advertisement. However, since the MAC address is unknown as theaddress of the FA control server, the mobile node MN needs to resolvethe MAC address from the IP address according to the ARP. Particularly,there may be a constraint on Mobile IP in which the home address of themobile node MN cannot be used for the ARP. In this case, the mobile node(MN) using the collocated care-of address can use the mechanism.

[0062] Since, the IP tunnel router notifies the mobile node (MN) 2 ofthe FA control server address as the FA care-of address and the ownaddress as the default router IP address, the mobile node (MN) 2 canrespectively recognize the FA control server and the IP tunnel router.Therefore, a Mobile IP network in which the control plane and the userplane are separated totally from the mobile node (MN) 2 to the HA can beconstructed.

[0063] Particularly, the mobile node (MN) 2 using the collocated care-ofaddress can use this mechanism.

FIFTH EMBODIMENT

[0064]FIG. 9 is a conceptual diagram illustrating the entire operationof the Mobile IPv4 in the fifth embodiment, and FIG. 10 illustrates theoperation flow of each apparatus at the time of executing positionregistration.

[0065] In this embodiment, the IP tunnel router 8 a regularly broadcaststhe IP address, being the default router, and the care-of address in theIP tunnel router 8 a, to the mobile node (MN) 2, via a path 24 in FIG.9, according to the specifications of the normal Mobile IP. This messageis a normal mobile agent advertisement message. As illustrated in FIG.3, the mobile node (MN) 2 receives the mobile agent advertisement, andrecognizes the sender MAC/IP addresses thereof as the normal FA, beingthe destination of the position registration and the destination of theuser packet.

[0066] The mobile node (MN) 2 having recognized the IP address of the IPtunnel router 8 a as the FA address creates a position registrationmessage including the IP address information of the known HA controlserver 9, and transmits the message to the MAC/IP addresses of themobile agent advertisement sender (reference numeral 25 in FIG. 9).

[0067] The IP tunnel router 8 a receives the position registrationmessage, detects that this message is a Mobile IP related message from aUDP port number (the UDP port number in the Mobile IP signaling is fixedto 434), and transfers this message to the FA control server 7(reference numeral 29 in FIG. 9). For this transfer, a signalingtransfer mechanism specified between the MGC and MG is used. In the caseof the Mobile IPv6, the Mobile IP signaling is identified by the optiontype of the IPv6 receiver option header. The FA control server 7 ahandles the transferred Mobile IP signaling as if it is received fromthe mobile node (MN) 2.

[0068] The IP tunnel router constituting the virtual FA serves as the FAwith respect to the mobile node (MN) 2, and when having received theMobile IP message from the mobile node (MN) 2, transfers this message tothe FA control server. The FA control server having received the MobileIP message from the HA control server transfers this message to the IPtunnel router, and the IP tunnel router delivers this message to themobile node (MN) 2. By this mechanism, a Mobile IP network in which thecontrol plane and the user plane are separated totally from the FA tothe HA can be constructed. The mobile node (MN) 2 can accommodate thenormal Mobile IP node.

SIXTH EMBODIMENT

[0069]FIG. 11 illustrates the operation flow of each apparatus at thetime of obtaining the address of the HA control server by the mobilenode (MN) 2 in the Mobile IPv4 according to the sixth embodiment. Inthis embodiment, it is assumed that the mobile node (MN) 2 does not knowthe IP address of the HA control server, and an automatic acquisitionmechanism of the IP address of the HA control server is specified.

[0070] The mobile node (MN) 2, which does not know the address of the HAcontrol server creates a position registration message in which thesubnet prefix of the home address and All 0 are set in the home addressregion, according to the specifications of the Mobile IP, and transmitsthis message to the subnet of the HA control server via the FA controlserver.

[0071] An edge router existing in the subnet of the HA control serverbroadcasts this message in the subnet. In the present invention, the HAcontrol server captures the broadcast packet, and returns a response ofrejecting the position registration in which the IP address of the HAcontrol server is set.

[0072] The mobile node MN receives the rejection response of positionregistration, understands the IP address of the HA control server, andexecutes position registration toward the HA control server.

[0073] The HA control server responds (gives a rejection response) tothe position registration of the Mobile IPv4 broadcasted in the HAsubnet, thereby informing the mobile node (MN) 2 of the address of theHA control server. Therefore, in the Mobile IPv4 network in which thecontrol plane and the user plane are separated, correspondence to aninstance in which the mobile node (MN) 2 does not know the address ofthe HA control server becomes possible.

SEVENTH EMBODIMENT

[0074] The seventh embodiment assumes a Mobile IPv6 network, in whichthe FA control server 7 in FIG. 1 is replaced by an AR control server asthe network, and the virtual AR is formed of an AR control server and anIP tunnel router 8. Particularly, for the virtual AR, the one thatsupports the Mobile IP function is assumed.

[0075] In the seventh embodiment, the AR control server notifies themobile node (MN) 2 of the own IP address, like the FA control server inthe first embodiment. As in the third embodiment, the AR control servernotifies the mobile node MN of the IP address of the IP tunnel router,being the default router, in addition to the own IP address. Further, asin the fourth embodiment, the IP tunnel router notifies the mobile node(MN) 2 of the IP address of the AR control server. As in the fifthembodiment, the Mobile IP message captured by the IP tunnel router istransferred to the AR control server, and the AR control server havingreceived the Mobile IP message from the HA function transmits the MobileIP message to the mobile node (MN) 2 via the IP tunnel router.

[0076] In the Mobile IP network in which the control plane and the userplane are separated, the load balancing between the control plane andthe user plane becomes possible, thereby enabling independentcorrespondence to upgrade of signaling and speed-up of the tunnelprocessing. As a result, an optimized system can be constructed.

EIGHTH EMBODIMENT

[0077]FIG. 12 illustrates the operation flow of each apparatus at thetime of obtaining the HA control server address by the mobile node (MN)2 in the Mobile IPv6 according to the eight embodiment.

[0078] The mobile node (MN) 2 that does not know the address of the HAcontrol server creates a position registration message in which thesubnet prefix of the home address and All 0 are set in the home addressregion, according to the specifications of the Mobile IP, encapsulatesthe message with an anycast address in the subnet of the home address,and transmits the message to the subnet of the HA control server.

[0079] This message is received by an optional router existing in thesubnet of the HA control server, and the router performs decapsulation,and this message is broadcasted in the subnet. In the present invention,the HA control server captures the broadcasted packet, and returns arejection response of position registration in which the IP address ofthe HA control server is set.

[0080] The mobile node (MN) 2 receives the rejection response ofposition registration, understands the IP address of the HA controlserver, and executes position registration toward the HA control server.

[0081] The mobile node (MN) 2 can recognize the FA control server andthe IP tunnel router respectively independently. Therefore, a Mobile IPnetwork in which the control plane and the user plane are separatedtotally from the mobile node (MN) 2 to the HA can be constructed.

[0082] In the Mobile IP network in which the control plane and the userplane are separated, the load balancing between the control plane andthe user plane becomes possible, thereby enabling independentcorrespondence to upgrade of signaling and speed-up of the tunnelprocessing. As a result, an optimized system can be constructed.

[0083] In the Mobile IPv4 network in which the control plane and theuser plane are separated, correspondence to an instance in which themobile node (MN) 2 does not know the address of the HA control serverbecomes possible.

[0084] According to the present invention, the mobile node (MN) 2 canrecognize the FA control server and the IP tunnel router respectivelyindependently. Therefore, a Mobile IP network in which the control planeand the user plane are separated totally from the mobile node (MN) 2 tothe HA can be constructed.

[0085] In the Mobile IP network in which the control plane and the userplane are separated, the load balancing between the control plane andthe user plane becomes possible, thereby enabling independentcorrespondence to upgrade of signaling and speed-up of the tunnelprocessing. As a result, an optimized system can be constructed.

[0086] Industrial Applicability

[0087] The mobility management method according to the distributedMobile IP of the present invention is useful for mobility management inthe mobile packet communication, and is particularly suitable for theMobile IPv4 or Mobile IPv6 network.

1-12. (CANCELLED)
 13. A mobility management system using a distributedMobile IP, in a Mobile IP network which allows a mobile node whilemoving to hold a current communication session, comprising: a foreignagent control server that is located in a first subnet where the mobilenode is located, performs Mobile IP signaling; a first IP tunnel routerthat is located in, the first subnet, and performs IP tunnel transfer; ahome agent control server that is located in a second subnet where themobile node is located, and performs Mobile IP signaling; and a secondIP tunnel router that is located in the second subnet, and performs IPtunnel transfer, wherein the foreign agent control server and the firstIP tunnel router constitute a virtual foreign agent, and the home agentcontrol server and the second IP tunnel router constitute a virtual homeagent.
 14. The mobility management system according to claim 13, whereinthe foreign agent control server transmits to the mobile node a messageindicating an IP address of the foreign agent control server, and thefirst IP tunnel router transmits to the mobile node a message indicatingan IP address of a default router.
 15. The mobility management systemaccording to claim 13, wherein the foreign agent control server, whenreceiving a first request for position registration from the mobilenode, determines a first IP tunnel endpoint in the first IP tunnelrouter, and transmits a second request including the first request andan IP address of the first IP tunnel endpoint to the home agent controlserver, the home agent control server determines a second IP tunnelendpoint in the second IP tunnel router, sets the first IP tunnelendpoint and the second IP tunnel endpoint into the second tunnelrouter, and transfers to the foreign agent control server a response tothe second request, and the foreign agent control server sets the secondIP tunnel endpoint into the first IP tunnel router, and transfers to themobile node the response.
 16. The mobility management system accordingto claim 13, wherein the home agent control server receives a requestincluding an IP address of a first IP tunnel endpoint being the mobilenode, determines a second IP tunnel endpoint in the second IP tunnelrouter, and transmits to the mobile node a response to the request. 17.The mobility management system according to claim 13, wherein theforeign agent control server transmits to the mobile node a messageindicating an IP address of the foreign agent control server and an IPaddress of the second IP tunnel router serving as a default router. 18.The mobility management system according to claim 13, wherein the firstIP tunnel router serves as a default router for the mobile node, andtransmits to the mobile node a message indicating an IP address of thedefault router and an IP address of the foreign agent control server.19. The mobility management system according to claim 13, wherein thefirst IP tunnel router transfers, when receiving a first Mobile IPmessage transmitted by the mobile node, the first Mobile IP message tothe foreign agent control server, the foreign agent control servertransfers, when receiving a second Mobile IP message transmitted by thehome agent control server, the second Mobile IP message to the first IPtunnel router, and the first IP tunnel router transfers the secondMobile IP message to the mobile node.
 20. The mobility management systemaccording to claim 13, wherein the mobile node transmits a request forposition registration to the foreign agent control server so that therequest is broadcasted over the second subnet, the home agent controlserver transmits to the foreign agent control server a response to therequest, the response including an IP address of the home agent controlserver and indicating rejection to the position registration, and theforeign agent control server transfers to the mobile node the response.21. The mobility management system according to claim 13, wherein theMobile IP network is an IPv4 network.
 22. A mobility management systemusing a distributed Mobile IP, in a Mobile IP network which allows amobile node while moving to hold a current communication session,comprising: an access router control server that is located in a firstsubnet where the mobile node is located, performs Mobile IP signaling; afirst IP tunnel router that is located in the first subnet, and performsIP tunnel transfer; a home agent control server that is located in asecond subnet where the mobile node is located, and performs Mobile IPsignaling; and a second IP tunnel router that is located in the secondsubnet, and performs IP tunnel transfer, wherein the access routercontrol server and the first IP tunnel router constitute a virtualaccess router, and the home agent control server and the second IPtunnel router constitute a virtual home agent.
 23. The mobilitymanagement system according to claim 22, wherein the access routercontrol server transmits to the mobile node a message indicating an IPaddress of the access router, and the first IP tunnel router transmitsto the mobile node a message indicating an IP address of a defaultrouter.
 24. The mobility management system according to claim 22,wherein the access router control server transmits to the mobile node amessage indicating an IP address of the foreign agent control server andan IP address of the second IP tunnel router serving as a defaultrouter.
 25. The mobility management system according to claim 22,wherein the first IP tunnel router serves as a default router for themobile node, and transmits to the mobile node a message indicating an IPaddress of the default router and an IP address of the access routercontrol server.
 26. The mobility management system according to claim22, wherein the first IP tunnel router transfers, when receiving a firstMobile IP message transmitted by the mobile node, the first Mobile IPmessage to the access router control server, the access router controlserver transfers, when receiving a second Mobile IP message transmittedby the home agent control server, the second Mobile IP message to thefirst IP tunnel router, and the first IP tunnel router transfers thesecond Mobile IP message to the mobile node.
 27. The mobility managementsystem according to claim 22, further a router located in the secondsubnet, wherein the mobile node transmits a request for positionregistration to the foreign agent control server so that the request isbroadcasted over the second subnet, the request being encapsulated withan anycast address in the second subnet, the router receives anddecapsulates the request, and broadcasts the request decapsulated overthe second subnet, the home agent control server transmits to the routera response to the request broadcasted, the response including an IPaddress of the home agent control server and indicating rejection to theposition registration, and the router transfers to the mobile node theresponse.
 28. The mobility management system according to claim 22,wherein the Mobile IP network is an IPv6 network.